Compass



Feb. 15, 1955 S. A. TELL COMPASS Filed Jan; 5, 1 953 Z ZW 3 Sheets-Sheet 1 s. A. TELL COMPASS Feb. 15, 1955 3 Sheets-Sheet 2 Filed Jan. 5, 1953 avg/Jag 68 i h w mm 759 25 45M M JAZZ,

United States Patent COMPASS Sven Axel Tell, Johanneshov, Sweden, assignor to Aktiebolaget Piab, Stockholm, Sweden, a corporation of Sweden Application January 5, 1953, Serial No. 329,687

Claims. {CL 33-27) This invention relates to a drawing compass with holders :for a center point and a pencil point, respectively. For drawing work compasses are used having two legs adjustable to different angles to each other, one of said legs carrying a center point and the other forming an attachment for apencil ,point, a lead point or a pen point. To describe circles of varying sizes one would be compelled to use at least two, frequently three or more different compasses, one of them being a bow compass for describing very small circles, a second compass, also intended for describing rather small circles, and, finally, one or more compasses for larger circles. Furthermore, socalled beam compasses have been used for very large circles. The reason why so many compasses have been required is that the legs of the compass acquire, on having been used for some time, a certain mutual warped setting, so that small circles in .particular cannot be described with the larger compasses with the requisite degree of accuracy. Now, the drawing technique has developed in such direction that inked-in drawings are seldom made use of, the drawings being made with a lead pencil on transparent paper for the taking of prints directly from the pencil drawing. In order to make the pencil lines adapted for such printing it is necessary that the pencil point be set considerably harder against the paper than was required when inking-in of drawings was practised; the warped setting .and the elasticity of the compass legs .is thereby increased, so that the circles frequently do not become accurate.

The object of the invention is to provide a compass which in itself can replace the three abovementioned main types and also the beam compass, and with the aid of which an exact drawing work with distinct lines can be performed, even where pure pencil drawings come into consideration.

I attain this object by mechanism described hereinbelow with reference to theannexed drawings, in which:

Fig. 1 shows the compass in elevation and partly sectioned on line II in Fig. 2; Fig. 2 is an elevation of the compass as viewed from the left in Fig. 1; Fig. 3 shows the compass in a section on line III-III in Fig. i; Fig. 4 shows an elevation of the compass in an extended position; Fig. 5 showsa-section on line VV.in Fig. 4; Fig. 6 shows a section on line VI-VI in Fig. 4; Fig. 7 shows the slide rod in a top plan view; Fig. 8 is a partly sectioned elevation of a modified construction of the compass; Pig. 9 is a detail view to a larger scale; and Fig. 10 shows in the same way as Fig. 8 a second modified construction.

In the drawing 1 designates a guide rod preferably consisting of a tubular piece and having a slide beam 2 longitudinally 'displaceable therein. Arranged at one end of the tube 1 is an attachment 31 consisting of a socket embracing the end of the tube and provided with a slit 4, said socket having a pin 5 extending therethrough. The pin 5 carries a setting nut 6 threaded on the same, by means of which nut the slit end of the tube 1 may be set about the slide beam 2, so that the latter will be retained in its adjusted position. A washer 7 is arranged inside the nut 6, said washer being provided with a pin 8 extending through the wall of the tube 1 and penetrating into a longitudinally extending slot 9 in the slide beam, so that the latter is prevented from turning relative to the tube 1, Fig. 4. A compass leg 11 is pivotally connected to the socket attachment 3 by means of a pin It said compass leg being at the upper end thereof pivotally mounted in a socket 13 by means of a pin 12. Pivotally mounted in the same socket is a second compass leg 14,

the lower end of which is pivotally connected to a holder 15 for a center ,pin 16. The compass legs 11 and 14 are formed at the top with toothed segments 17 engaging one another, so that the compass legs will follow the movements of each-other and so that the socket 13 will always take a .position parallelling the pin 16 directed at right angles to the tube 1.

The holder 15 is longitudinally displaceable on the tube 1 and has a circular bore for the tube. The holder is-providedwith a slit 18, Fig. 5, and has a stop pin 19 extending therethrough across the slit 18, said stop pin bearing at one end with a head 20 on a protuberance in the holder 15 While having a nut 21 threaded onto the other end thereof, by means of which nut the holder may be secured to the tube 1 in the desired position by compression of the slit. In Fig. 4, the holder 15 is shown as being displaced for a distance from the fixed attachment 3, the slide beam 2 being in an extended position.

Arranged on the outer end of the slide beam 2 is an externally threaded pin 22 onto which is arranged a holder 23 for a pencil-point such as a lead point 24. The outer endof the slide beam is provided at one end thereof with a series of teeth 25, Fig. 7, corresponding teeth being provided on the holder 23. -By means of a nut 26 threaded onto the pin 22 the holder 23 may be firmly retained on the beam 2 at an arbitrary angle to the longitudinal axis of the beam.

As-will appear from Fig. 5, the pin 16 is provided with a shoulder 27 engaging the tube 1, so that the pin is prevented from being displaced upwardly. Furthermore, the pin has two shoulders 28 and 29 facing each other, said shoulders being formed by a reduction 39 of the diameter of the pin. The stop pin 19 is disposed within the range between the shoulders 28 and 29 and restricts thedownward movement of the pin by striking against the shoulder 28 and the upward movement of the pin relative tothe holder 15 by striking against the shoulder 29. In the position according to Fig. 5, the pin is shown as being locked against movement in both directions. In this position of the pin the compass functions as an ordinary compass.

In order that the compass shall be serviceable as a spring bow compass for describing very small circles, in which compass the center pin shall be permitted to be moved upwardly and downwardly, as is well known, a recess 31 is provided in thetube 1 adjacent the attachment 3, Fig. 4. The shoulder 27 consequently does not engage the tube at this place and the pin being thus permitted to be displaced upwardly and downwardly.

For the operation of the center pin the following means are provided. In the holder 13, which is in the ordinary manner provided with a preferably channelled knob or handle 32, there is arranged an upwardly and downwardly displaceable depressing member consisting of a knob 33 and a pin 34 secured therein. The pin 34 extends downwardly to the upper articulation of the compass leg 14. The compass leg has a guide 35 arranged therein, saidguide taking, for instance, the form of a longitudinally extending bore having a pressure-transferring member, preferably a rod 36, inserted therein. In Fig. l, the parts take the position they have when the compass is to serve as a bow compass for describing very small circles. 8y pressing the button 33, the pin 16 may be moved downwardly in its holder and be caused to pierce the drawing paper, whereupon thecompass is rotated with the aid of the knob 32. Here, an adjustment of the radius of the circle is effected by a displacement of the slide beam 2, such displacement being facilitated by the end 2a of the rod 2 projecting somewhat outside the outer end of the tube 1. The part 2a of the beam 2 which projects beyond the end of tube 1 facilitates an exact adjustment of the beam 2 and the pencil point 24 when it is desired to adjust the compass for very small circles. It is merely necessary to press at 2a with a finger of the same hand with which the other fingers thereof hold the tube 1. If on the other hand, the projection 2a were to be omitted and the adjustment for small circles made by grasping the holder for the pencil point with the hand, such hand would simultaneously hide the pencil point from view and make the desired adjustment that much more difficult.

Inasmuch as the pressure transferring members 34, 36

and the center point 16 are separated from one another, the compass leg 14 may take the angular position according to Fig. 4 with the members 13 and 15 paralleling each other. Balls 43 may be inserted between the members 13 and 36 and 16 at the articulations of the compass leg 14, as shown in Fig. 10. If desired, the rod 36 may be replaced by a row of small balls laid close to each other. The pin 34 is provided at the bottom with an enlargement, which prevents the same from being drawn out upwardly. In mounting, the pin 34 is threaded into the button 33.

The articulations of the ends of the compass leg 14 are formed by pins 37, Fig. 5, which are threaded in from both sides, without reaching in to the channel in the compass leg.

As shown in Fig. 7, the slide beam 2 may be provided with a scale 38, which may be read off against the end of the sleeve 1 for the adjustment of the diameter of the circle. To facilitate sharp reading, the end of the tube 1 may be provided with an incision 39.

As will be seen from Fig. 1, the pencil point 24 passes through a sleeve formed with clamping jaws 40, the channel of which sleeve extends throughout the same, so that the pencil point extends out of the same also on the upper side thereof. The clamping jaws may be drawn tight by means of a channelled nut 41, it being possible at the same time to adjust the pencil point by pressing thereon with the finger. The clamping jaws 40 may be made from glass-hard hardened steel, which is not damaged by a file, that may be used to sharpen the pencil point. The holder for the pencil point may, of course, be replaced by a holder for a pen point or a metal point, if it is desired to use the compass for inking-in or for tracing and the like.

Instead of using the rounding of the tube 1 as an abutment for the center point (Fig. it is possible to provide a guide fillet, for instance on the outside of the tube, said guide fillet engaging a corresponding groove in the pin 16. The recess 31 then corresponds to an interruption in said guide fillet.

By the arrangement according to the invention the center pin will always take a position at right angles to the drawing board during the drawing work, and the adjustment of the compass for different radii is then effected at a parallel movement between the center point and the drawing pen or pencil point.

In the example of embodiment shown in Figs. 8 and 9, there is provided a closely coiled helical spring 42 and 42a, respectively, at the articulations between the compass leg 14 and the handle 32 and the holder 15, respectively. The spring 42 bears at one end thereof on the pin 34 and at the other end thereof on the rod 36, the upper end of which is located at some distance from the upper end of the compass leg. In the same manner the helical spring 42a forms a flexible compressive connection between the rod 36 and the center point. In the example of embodiment according to Fig. 8, the center point 16 is not locked in the position of the compass legs shown in the drawing, since it is not possible to transmit any movement to the center point from the depressing member 33, 34 inasmuch as the springs 42, 42a are locked by their flexure at the articulations of the compass leg. However, when the compass leg 14 is swung into parallelism with the compass leg 11, that is to say, into the position shown in Fig. 1, it is possible to press the center point 16 downwardly by means of the member 33, 34, the movement of which is propagated through the helical springs 42, 42a which are then straight. In this position, the compass may consequently serve as a bow-compass for describing very small circles.

What I claim is:

1. A drawing compass comprising a center pin, a

pencil point, a holder for the center pin, a holder for the pencil point, a guide tube having the holder for said center pin axially displaceably mounted thereon, a rod axially displaceably mounted in said guide tube, the holder for said pencil point being connected to one end of said rod, a first compass leg having one end articulated to the holder for the center pin, a compass handle articulated to the other end of said first compass leg, said center pin being displaceably mounted in its holder, a depressing member slidable in said handle, pressure transferring means in said first compass leg flexible relatively to said center pin and said depressing member to permit articulation of said first leg relative to the handle and the holder for the center pin and to transfer movement of said depressing member to said center pin when said pressure transferring means is in alignment with the depressing member and the center pin, and a second compass leg articulated to said handle and to said guide tube.

2. A drawing compass as set forth in claim 1, wherein said pressure transferring means includes a plunger slightly shorter in length than said first compass leg and displaceable within said leg.

3. A drawing compass as set forth in claim 1, wherein said pressure transferring means includes a plunger slightly shorter in length than said first compass leg and displaceable within said leg, and a ball contacting said plunger at least at one of the points of articulation of said first compass leg.

4. A drawing compass as set forth in claim 1, wherein said pressure transferring means includes a plunger slightly shorter in length than said first compass leg and displaceable within said leg, a closely coiled helical spring between one end of said plunger and said depressing memher, and a second closely coiled helical spring between the other end or" said plunger and said center pin, said springs being located at the points of articulation of said first compass leg.

5. A drawing compass comprising a center pin, a pencil point, a holder for the center pin, a holder for the pencil point, a guide tube having the holder for said center pin axially displaceably mounted thereon, a rod axially displaceably mounted in said guide tube, the holder for said pencil point being connected to one end of said rod, a first compass leg having one end articulated to the holder for the center pin, a compass handle articulated to the other end of said first compass leg, said center pin being displaceably mounted in its holder, a depressing member slidable in said handle, pressure transferring means in said first compass leg flexible relatively to said center pin and said depressing member to permit articulation of said first leg relative to the handle and the holder for the center pin and to transfer movement of said depressing member to said center pin when said pressure transferring means is in alignment with the depressing member and the center pin, said center pin having two axially spaced abutments, a stop member between said abutments to limit said axial movement of the center pin, and a second conpass leg articulated to said handle and to said guide tu e.

References Cited in the file of this patent UNITED STATES PATENTS 732,463 Stoddard June 30, 1903 1,009,256 OLeary Nov. 21, 1911 1,288,412 Hill Dec. 17, 1918 1,503,934 Akashi Aug. 5, 1924 FOREIGN PATENTS 24,765 Great Britain A. D. 1895 

